Mono- and polythiobis dialkylphenols are useful as antioxidants in a broad range of substrates such as lubricating oil and polymers (Knapp, U. S. 3,145,176). They have been made in non-polar solvents such as benzene, toluene, hexane and the like. These methods however produce an oily product containing significant quantities of starting material and impurities while purer products are obtained using the later methods. The reactions must be carried out at relatively cold temperatures (-20.degree. to -40.degree. C.). This makes the process less economical. They have also been made in acetonitrile (Tamatsu et al. U.S. Pat. No. 3,718,699) using an iron or ferric chloride catalyst. British No. 1,290,132 report that with 2,6-di-tert-butylphenol and S.sub.2 Cl.sub.2, Virtually no reaction takes place at room temperature unless the reaction is continued for over 6 hours. British No. 1,290,132 requires the use of a Lewis acid to cause the reaction to proceed in a solvent such as hexane, carbon tetrachloride, toluene, benzene, chlorobenzene, methanol, diethylether or glacial acetic acid.